206611661 has 2 divisors, whose sum is σ = 206611662. Its totient is φ = 206611660.

The previous prime is 206611627. The next prime is 206611679. The reversal of 206611661 is 166116602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 122522761 + 84088900 = 11069^2 + 9170^2 .

It is a cyclic number.

It is not a de Polignac number, because 206611661 - 2⁶ = 206611597 is a prime.

It is a super-2 number, since 2×206611661² = 85376756922357842, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (206617661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103305830 + 103305831.

It is an arithmetic number, because the mean of its divisors is an integer number (103305831).

Almost surely, 2^206611661 is an apocalyptic number.

It is an amenable number.

206611661 is a deficient number, since it is larger than the sum of its proper divisors (1).

206611661 is an equidigital number, since it uses as much as digits as its factorization.

206611661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 206611661 is about 14373.9925212169. The cubic root of 206611661 is about 591.1780169433.

It can be divided in two parts, 20661 and 1661, that added together give a palindrome (22322).

The spelling of 206611661 in words is "two hundred six million, six hundred eleven thousand, six hundred sixty-one".